The present invention relates to the transfer attachment construction of a 4WD vehicle and more particularly to the transfer attachment construction of 4WD vehicles that are based on FF vehicles (Front engine-Front drive).
In 4WD vehicles in order to apply the engine""s driving power to meet the running requirements, there exists, as power transmitters, a transmission, a differential, and, a transfer to distribute the driving power from the transmission.
However, in the case of 4WD vehicles that are based on FF vehicles (Front engine-Front drive), the transmission and differential are of one piece, and to the differential is connected a drive wheel axle. On top of the drive wheel axle is attached an independently formed transfer.
In the case of a transfer 102, as shown in FIGS. 20 and 21, a retainer 108 is included and is attached to the rear of the transfer case 106 by retainer attachment bolts in the direction of transfer pinion axle center C at the rear of the vehicle and supported by the transfer pinion axle (not shown) which runs lengthwise of the vehicle, namely, at top right, retainer attachment bolt NO. 1 (104-1), at bottom right, retainer attachment bolt NO. 2 (104-2) at top left, retainer attachment bolt NO. 3 (104-3), and at bottom left, retainer attachment bolt NO. 4 (104-4)(not shown). Also, protruding at the right of retainer 108 is the top right NO. 1 bracket attachment boss 110-1 and the bottom right NO. 2 bracket attachment boss 110-2, to which is attached the mount bracket 114 by mount attachment bolt NO. 1 (112-1) and by mount attachment bolt NO. 2 ( 112-2) in an almost perpendicular orientation to transfer pinion axle center C. The mount bracket forms an S shaped space which supports a mount (not shown), and comprises NO. 1 and NO. 2 bolt supporting bosses 118-1 and 118-2 which contain NO. 1 and NO. 2 bracket attachment bolt holes 116-1 and 116-2 (not shown) through which must pass NO. 1 and NO. 2 bracket attachment bolts 112-1 and 112-2. It also comprises a first attachment section 120, which is located at the right side of retainer 108, and an opposite attachment section 122, which is located in opposition to the first attachment section 120 and set apart from the right side of retainer 108. At the tips of both attachment sections are mount supporting bosses 124 and 126. Also, the first attachment section 120 is attached to another bracket attachment boss, the NO. 3 bracket attachment boss 128, which is formed at the rear of retainer 108. The first attachment section 120 is attached to the No. 3 bracket attachment boss 128 by the NO. 3 bracket attachment bolt 130. In this case, as shown in FIG. 21, the center lines M1 and M2 of NO. 1 and NO. 2 bracket attachment bosses 110-1 and 110-2 are at distances E1 and E2 from the transfer pinion axle center C, and also, at transfer pinion axle center C, overlap the head sections of NO. 1 and NO. 2 retainer attachment bolts 104-1 and 104-2.
Further, as shown in FIGS. 22 and 23, in the case of a transfer 202, a retainer 208 is included, and is attached to the rear of the transfer case 206 by retainer attachment bolts, in a rearward direction from transfer pinion axle center C and supported by the transfer pinion axle (not shown) which runs lengthwise of the vehicle, namely, at top right, retainer attachment bolt NO. 1 (204-1), at bottom right, retainer attachment bolt NO. 2 (204-2), at top left, retainer attachment bolt NO. 3 (204-3), and at bottom left, retainer attachment bolt NO. 4 (204-4)(not shown). Also, a one piece mount bracket 216 is formed to the right side of retainer 208 and comprises supporting boss 210, first attachment section 212 and opposite attachment section 214.
Examples of this kind of transfer construction are disclosed in published Japanese Patent Application Laid-Open No. 10-291426 and Japanese Patent Application Laid-Open No. 10-203190. In Japanese Patent Application Laid-Open No. 10-291426, an extension housing is connected to the transfer case, and also, in the cylindrically shaped rotating body, a lubricating oil passage is formed that connects with the extreme section on the transfer side In Japanese Patent Application Laid-Open No 10-203190, a lubricating oil groove is formed on the inner side of the transfer case and a mound is formed on one of the ball bearings in the spacer.
However, it has conventionally been the case that in a transfer as shown in FIGS. 20 and 21 the NO. 1 and NO. 2 bracket attachment bosses in the direction of the transfer pinion center overlap with the NO. 1 and NO. 2 bracket retainer attachment bolt heads. In such a case, when attaching the retainer to the transfer case the NO. 1 and NO. 2 retainer attachment bolts interfere with the NO. 1 and NO. 2 bracket attachment bosses, making it difficult to tighten the NO. 1 and NO. 2 retainer attachment bolts and thereby decreasing assembly efficiency as well as the coupling reliability of the retainer and mount bracket.
Also, in a transfer as shown in FIGS. 22 and 23, as the retainer and mount bracket are formed of a single piece, the construction of the complete retainer is complicated and the manufacture is made difficult. Furthermore, yield is decreased and manufacture is expensive.
Therefore, in order to eliminate the above-described disadvantages in the transfer attachment construction of a 4WD vehicle, the present invention is characterized by the retainer being attached to a transfer case by retainer attachment bolts in line with the center of a transfer pinion axle where the transfer pinion axle is disposed in a front-to-rear direction of the vehicle, by the retainer including a bracket attachment boss to which a mount bracket is attached by bracket attachment bolts and at an almost perpendicular orientation to the transfer pinion axis, and by the retainer attachment bolts being prevented from interfering with the bracket attachment boss by disposing the bracket attachment boss close enough to the transfer pinion axle to avoid overlapping between the bracket attachment boss and the retainer attachment bolts as the bolts are screwed into the transfer case in a direction in line with the transfer pinion axle.
According to the present invention, in order to prevent the retainer attachment bolts from interfering with multiple bracket attachment bosses, the bracket attachment bosses are disposed close enough to the transfer pinion axle to thereby avoid overlapping between the bracket attachment bosses and the retainer attachment bolts. By this means, when attaching the retainer to the transfer case, the retainer attachment bolts will not interfere with the bracket attachment bosses, the retainer attachment bolts are easier to tighten, thus increasing ease of assembly, and the coupling of the retainer and mount bracket is improved. To this same end, retainer construction design is simplified, making for ease of manufacture; also, yield is increased, and construction costs are lessened.